Generally, the hard disk drive (HDD) includes the suspension substrate on which a magnetic head slider mounted. In this case, the magnetic head slider is provided for writing and reading data relative to a disk adapted for storing therein the data. The suspension substrate includes a metallic support layer and a wiring layer layered on the metallic support layer, via an insulating layer. The wiring layer has a plurality of (e.g., four to six) wirings. With this configuration, by flowing or sending an electric signal through each wiring, the writing and reading of the data relative to the disk can be performed.
In the hard disk drive of this type, an actuator arm for supporting the magnetic head slider and a VCM actuator (e.g., a voice coil motor) are provided respectively. In this case, in order to move the magnetic head slider to a desired data track on the disk, the actuator arm is pivoted by the VCM actuator, under control of a servo-control system.
In recent years, for an attempt to provide a more high-density disk, the width of each data track has been narrowed. However, in some cases, such an attempt makes it rather difficult to accurately align the magnetic head slider with the desired track, by using the VCM actuator.
To address this problem, the suspension of the so-called dual actuator type has been reported. In this case, the VCM actuator is cooperated with a PZT micro-actuator (or DSA (Dual Stage Actuator)), in order to accurately move the magnetic head slider to the desired track (e.g., see JP2009-295195A or JP2010-79944). Specifically, the PZT micro-actuator is composed of a piezoelectric element composed of a lead titanate zirconate (PZT) and configured to be expanded and contracted with application of a voltage, thus enabling the magnetic head slider to be finely moved. Namely, in the suspension of this dual actuator type, the VCM actuator serves to roughly control the position of the magnetic head slider, while the PZT micro-actuator serves to finely control the position of the magnetic head slider. In this way, the magnetic head slider can be aligned, rapidly and accurately, with the desired track.